Suicide Bombing in Riyadh

Suicide Bombing in Riyadh, Saudi Arabia. May 12, 2003, 11:30 p.m.
(20:30 GMT).
Attackers shot their way into three housing compounds in
synchronized strikes in the Saudi capital and then set off multiple
suicide car bombs, killing 20 people at first estimate,
including seven Americans. As of a few days later the number killed was
said to be 34, with about 200 wounded.

Authorities also found nine charred bodies believed to be those of the
attackers, a Saudi Interior Ministry official said. The bombings,
which took place about 11:30 p.m. Monday, constituted one of the
deadliest terror attacks on Americans since Sept. 11, 2001.
Secretary of State Colin Powell said the coordinated strike had
"the fingerprints of al-Qaida," the group that attacked the World
Trade Center and the Pentagon.

The formal prediction was for a period of one hour prior to the
attacks, to three hours after, standard analysis.
The result shows Chisquare 14524 on 14400 df, with p = 0.231. The
pattern is suggestive of an early response, beginning an hour before the
bombing and peaking half an hour after.

A larger context is instructive. The following figure shows the 12th
and 13th of May, GMT, with the four-hour period of the formal analysis
marked. The bombing happened one hour into this period, at 11:30 pm local
time (21:30 GMT). In context, the graph of the data shows nothing
impressive, and this is consistent with the formal test probability.
The suggestion of an "early response" may be just an accidental outcome.